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BS NA EN 1993-1-5 (2006) (English): UK NationalAnnex to Eurocode 3. Design of steel structures.Plated structural elements

NA to BS EN 1993-1-5:2006

NATIONAL ANNEX

UK National Annex to Eurocode 3: Design of steel structures -Part 1-5: Plated structural elements res 91.010.30; 91.080.10

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NA to BS EN 1993-1-5:2006

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© BSI 2008

ISBN 978 0 580 54964 9

The following BSI references relate to the work on this standard: Committee reference B/525/l 0 Draft for comment 07/30128103 DC

Publication history

First published May 2008

Amendments issued since publication

Amd. no. Date Text affected

NA to BS EN 1993-1-5:2006

Contents Introduction 1

NA.l Scope 1 NA.2 Nationally Determined Parameters 2 NA.3 References to non-contradictory complementary information 4

Bibliography 5

Summary of pages

This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 5 and a back cover.

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NA to BS EN 1993-1-5:2006

ii • © BSI 2008 This page deliberately left blank

NA to BS EN 1993-1-5:2006

National Annex (inforInative) to BS EN 1993-1-5:2006, Eurocode 3 - Design of steel structures - Part 1-5: Plated structural eleInents

Introduction This National Annex has been prepared by BSI Subcommittee B/525/1 0, Bridges, in consultation with B/525/31, Structural use ojsteel.

NA.l Scope This National Annex gives:

a) the UK decisions for the Nationally Determined Parameters described in the following subclauses of BS EN 1993-1-5:2006:

• 2.2(5)

• 3.3(1)

• 4.3(6)

• 5.1(2)

• 6.4(2)

• 8(2)

• 9.1(1)

• 9.2.1(9)

• 10(1)

• 10(5)

• C.2(1)

• C.5(2)

• C.8(1)

• C.9(3)

• D.2.2(2)

b) References to non-contradictory complementary information (see NA.3).

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NA.2 Nationally Determined Parameters

NA.2.1 Effective width models for global analysis [BS EN 1993-1-5:2006, 2.2(5)]

The recommended value of effective width parameter Aim should be used.

NA.2.2 Shear lag at the ultimate limit state [BS EN 1993-1-5:2006, 3.3(1)] The recommended method in NOTE 3 should be used.

NA.2.3 Effective cross section [BS EN 1993-1-5:2006, 4.3(6)]

The recommended value of 91l should be used.

NA.2.4 Basis [BS EN 1993-1-5:2006, 5.1(2)] The value of 1] should be taken as 1,0 for all steels.

NA.2.5 Reduction factor kF for effective length for resistance [BS EN 1993-1-5:2006, 6.4(2)] NA.2.5.1 Equation (6.6) should be used for patch loading Types (a) and (c) from Figure 6.1 for beams with longitudinal stiffeners. At locations beyond the limits for which equation (6.6) in 6.4(2) is valid, the treatment of such patch loading will be as for an unstiffened web.

NA.2.5.2 Equation (6.6) should not be used for patch loading types (b) from Figure 6.1 for beams with longitudinal stiffeners. Patch loading Type (b) from Figure 6.1 may be treated as for an unstiffened web or may be subject to a special buckling analysis.

NA.2.6 Flange induced buckling [BS EN 1993-1-5:2006, 8(2)]

NA.2.6.1 The design for flange induced buckling should take account of the possible collapse of the web due to radial forces from a flange in compression or tension curved in elevation, whether or not a beam as a whole is curved.

NA.2.6.2 For nominally horizontal flanges, Clause 8(2) may be applied, but the adequacy of the web should be checked using the same analysis as for beams with flanges curved in elevation with a radius of curvature corresponding to an out-of-flatness equal to the span/625.

NA.2.6.3 The adequacy of the web with curved flanges should be verified by analysis of the buckling strength of the web, whether stiffened or not, under radial forces induced by the tlanges and associated webs in addition to any coincident global shear and longitudinal forces. The adequacy of the web should also be verified by use of the rules in Clause 6 in conjunction with 7.2(1).

NA to BS EN 1993-1-5:2006

NA.2.6.4 For beams with only the compression flange curved the buckling coefficients, Type (a) in Figure 6.1 should be used. For beams with both flanges curved, the Type (b) coefficients should be used. For such a method of verification, nn should be taken as 2,0 in deriving 172.

NA.2.7 Stiffeners and detailing [BS EN 1993-1-5:2006, 9.1(1)] NA.2.7.1 Where the web of a beam is subjected to a net compressive force, whether due to externally applied compressive force or due to the flexural neutral axis not being at the mid-height of the web, the effect of the net compressive force should be considered in the design of rigid transverse stiffeners resisting shear.

NA.2.7.2 When applying 9.3.3(3), the design force in the NOTE should not be used. Instead, intermediate rigid stiffeners should be designed for an axial force, PEd' acting in the mid-plane of the web in addition to any externally applied loads, where:

CF P T T h t x ° 8-r 1 - x,Ed -f"or a >- h Ed = "Ed - w ,,, 1':;.-- w

0,8CFcr,x

[

TT h t 0 8 1 CFx'Ed]~ for a < h PEd = II Ed - w X , rcr 0,8CFcr,x hw w

where:

rcr is the elastic critical shear buckling stress determined in accordance with 5.3;

O"cr,x is the elastic critical plate buckling stress for direct stress determined in accordance with 4.4 or 4.5 for sub-panel buckling and overall stiffened plate buckling respectively; and

O"x,Ed is the greatest longitudinal compressive stress in the web panel under consideration.

O"x,Ed is taken as positive when compressive and should not be taken as being greater than 0,80"cr,x'

NA.2.7.3 When applying 9.2.1, O"cr,c and O"cr,p should generally be calculated for a panel length of a l + a2 with Wo taken as the lesser of b/300, a/300 and azl300. However, to safeguard against a mode of buckling with adjacent transverse stiffeners bowing in alternate directions, 9.2.1 should also be applied with O"cr,c and O"cr,p calculated for a panel length of 0,5 Cal + a2). In this case, Wo should be taken as the lesser of b/150, a/150 and a2/150.

For panels with longitudinal stiffeners, the ratio O"cr,JO"cr,p should be taken to be equal to 1, ° unless an alternative value can be justified by calculations which can also be supported by either test evidence or non-linear analysis.

NA.2.8 Minimum requirements for transverse stiffeners [BS EN 1993-1-5:2006, 9.2.1(9)] The value of () should be taken as 2,0.

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NA.2.9 Reduced stress method [BS EN 1993-1-5:2006, 10(1)] There are no limits of application to the methods.

NA.2.10 Reduced stress method [BS EN 1993-1-5:2006, 10(5)] For panels with tension and compression, equations (10.4) and (10.5) should be applied only to the compressive parts.

NA.2.11 Use [BS EN 1993-1-5:2006, C.2(1)] Conditions for the use of FEM analysis in design should be specified for the particular project.

NA.2.12 Use of imperfections [BS EN 1993-1-5:2006, C.5(2)] The recommended approach should be adopted.

NA.2.13 Limit state criteria [BS EN 1993-1-5:2006, C.8(1)] The limit to principal strain for regions subjected to tensile stresses should be 5%.

NA.2.14 Partial factors [BS EN 1993-1-5:2006, C.9(3)] NA.2.14.1 For bridges, IMI and 1M2 as specified in the National Annex to BS EN 1993-2 should be used.

NA.2.14.2 For buildings, IMI and 1M2 as specified in the National Annex to BS EN 1993-1-1 should be used.

NA.2.15 Shear resistance [BS EN 1993-1-5:2006, D.2.2(2)] No additional information is provided.

NA.3 References to non-contradictory complementary information PD 6695-2, Recommendationsjor the design ojbridges to BS EN 19931).

1) In preparation.

NA to BS EN 1993-1-5:2006

Bibliography For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

NA to BS EN 1993-1-1, UK National Annex to Eurocode 3: Design oj steel structures Part 1-1: General rules and rules jor buildings

NA to BS EN 1993-1-2, UK National Annex to Eurocode 3: Design oj steel structures Part 2: Steel bridges

PD 6695-2, Recommendationsjor the design oj bridges to BS EN 19932)

2) In preparation.

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